1. Field of the Invention
The present invention relates to the microbiological industry, and specifically to a method for producing an L-amino acid using a bacterium of the Enterobacteriaceae family which has been modified to attenuate expression of the yafA gene.
2. Brief Description of the Related Art
The bacterial phosphoenolpyruvate (PEP):sugar phosphotransferase system (PTS) plays an important role in the transport of a variety of sugar substrates. The PTS of Escherichia coli is composed of two general cytoplasmic proteins, enzyme I (EI) and histidine phosphocarrier protein, HPr, which are used for all sugars, and some sugar-specific components collectively known as enzymes II, comprising soluble enzyme IIAGlc and membrane bound enzyme IICBGlc (Escherichia coli and Salmonella, Second Edition, Editor in Chief: F. C. Neidhardt, ASM Press, Washington D.C., 1996, pp. 1149-1174). Glucose uptake entails sequential phosphoryl transfer via the PTS, as follows: phosphoenolpyruvate (PEP)→EI→HPr→IIAGlc→IICBGlc→glucose.
Each protein component of the E. coli PTS involved in glucose uptake has been shown to regulate the activity of a partner protein via direct protein-protein interaction. These regulatory functions of PTS depend on the phosphorylation state of the involved component. The err gene product (enzyme IIAGlc) mediates some of these regulatory phenomena. The product of the yafA (also known as frsA) gene, FrsA (fermentation/respiration switch protein) regulator protein was shown to form a complex which specifically interacts with the unphosphorylated form of IIAGlc (Koo, B. M. et al. J Biol Chem. Jul. 23, 2004; 279(30): 31613-21). The authors also reported that disruption of the yafA gene increased cellular respiration on several sugars including glucose.
Currently, there have been no reports of inactivating the yafA gene for production of L-amino acids.